A piperidine-free synthesis for the biologically active molecule Caulerpin is presented. Methyl 2-(3-formyl-1H-indol-2-yl) acetate was synthesized and condensed into eight-membered aromatic ring structure through an intermolecular Knoevenagel reaction was catalyzed using an amino acid-ionic liquids solvent, giving yield of 61 %. Furthermore, five 2,3,6-trifunc-tional indole derivatives with 6-position substituents were used to obtain 6,6'-disubstituted derivatives, with yields ranging from 23 % to 31 %. Bioactivity tests demonstrated that 6,6'difluorocaulerpin significantly inhibited the immortalized human lung cancer cell line HeLa, with the IC 50 value 9.5 μg⋅mL À 1 .[a] Z.
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